Ceramics heater for semiconductor production system

ABSTRACT

Affords ceramic susceptors, for semiconductor manufacturing equipment, in which wafer-surface isothermal quality during heating operations is heightened by enhancing the degree of planarization of the susceptor wafer-carrying face in its high-temperature region where wafers are processed in the course of manufacturing semiconductors. Ceramic susceptor ( 1 ) for semiconductor manufacturing equipment has in the surface or interior of ceramic substrates ( 2   a ) and ( 2   b ) resistive heating element ( 3 ), and a non-heating (ordinary-temperature) arched contour in its wafer-carrying face is a concavity of 0.001 to 0.7 mm per 300 mm. A plasma electrode furthermore may be disposed in ceramic susceptor  1 , in the surface or interior of ceramic substrates ( 2   a ) and ( 2   b ). Preferably, moreover, ceramic substrates ( 2   a ) and ( 2   b ) are at least one ceramic selected from aluminum nitride, silicon nitride, aluminum oxynitride, and silicon carbide.

TECHNICAL FIELD

The present invention relates to ceramic susceptors employed to retainand heat wafers in semiconductor manufacturing equipment in whichpredetermined processes are carried out on the wafers in the course ofsemiconductor manufacture.

BACKGROUND ART

A variety of structures for ceramic susceptors employed in semiconductormanufacturing equipment has been proposed to date. For example, asemiconductor wafer heating device equipped with a ceramic susceptor inwhich a resistive heating element is embedded and that is installedwithin a reaction chamber, and with a pillar-like support member that isprovided on a surface of the susceptor apart from its wafer-heating faceand forms a gastight seal between it and the chamber, is proposed inJapanese Pat. App. Pub. No. H06-28258.

In order to reduce manufacturing costs meanwhile, a transition to wafersof larger diametric span—from 8-inch to 12-inch in outer diameter—is inprogress, along with which the ceramic susceptors that retain the wafersare turning out to be 300 mm in diameter or more. At the same time,isothermal ratings within ±1.0%, more desirably within ±0.5%, in thesurface of wafers being heated by the ceramic susceptors are beingcalled for.

In response to demands for such isothermal properties, given that when awafer has been set in place on a ceramic susceptor gaps arising betweenthe wafer-carrying face and the wafer make uniform heating impossible,precision-finishing the susceptor wafer-carrying face to raise itsdegree of planarization has been pursued. Nevertheless, accompanying thetransition to wafers of larger diametric span, realizing what is beingcalled for as just mentioned in wafer-surface isothermal quality isproving to be problematic.

Patent Reference 1

Japanese Pat. App. Pub. No. H06-28258.

Although, as just described, raising the degree of planarization in thesusceptor wafer-carrying face has been pursued to date in order toimprove wafer isothermal ratings, in recent years meeting isothermalquality demands as wafers continue to be scaled up diametrically isproving to be difficult.

For example, as set forth in the just-mentioned Japanese Pat. App. Pub.No. H06-28258, owing to the fact that with a support member being joinedto the ceramic susceptor, heat that is generated when electric currentflows through the resistive heating element is transmitted from thesusceptor through the support member and escapes out into the reactionchamber, the thermal expansion coefficient of the support-member end ofthe susceptor is small by comparison to its wafer-carrying face, whereinstress tending to bulge the wafer-carrying face is placed on thesusceptor. Consequently, even though the wafer-carrying face has beenprecision-finished to raise its degree of planarization atroom-temperature, the surface isothermal quality of wafers when beingprocessed on the susceptor has not risen, because in practice thewafer-carrying face buckles into a convex contour in itshigh-temperature region, producing gaps between it and the wafer andgiving rise to non-uniformity in the conduction of heat into the wafer.

DISCLOSURE OF INVENTION

An object of the present invention, in view of such circumstances todate, is to heighten the degree of planarization of ceramic-susceptorwafer-carrying faces in their high-temperature region where wafers areprocessed in the course of manufacturing semiconductors, to affordsusceptors for semiconductor manufacturing equipment in whichwafer-surface isothermal quality during heating operations isheightened.

In order to achieve the foregoing objective, the present inventionrenders a ceramic susceptor for semiconductor manufacturing equipment,having a resistive heating element in the surface or interior of itsceramic substrate, being a semiconductor-manufacturing-equipment ceramicsusceptor characterized in that the wafer-carrying face in archedcontour when not heating is a concavity of 0.001 to 0.7 mm/300 mm.

In the foregoing semiconductor-manufacturing-equipment ceramic susceptorof the present invention, the ceramic substrate preferably is made of atleast one ceramic selected from aluminum nitride, silicon nitride,aluminum oxynitride, and silicon carbide.

Likewise, in the foregoing semiconductor-manufacturing-equipment ceramicsusceptor of the present invention, the resistive heating element ispreferably made from at least one metal selected from tungsten,molybdenum, platinum, palladium, silver, nickel, and chrome.

In addition, a plasma electrode furthermore may be disposed in thesurface or interior of the ceramic substrate for the foregoingsemiconductor-manufacturing-equipment ceramic susceptor of the presentinvention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view illustrating one specific exampleof a ceramic susceptor according to the present invention; and

FIG. 2 is a schematic sectional view illustrating a separate specificexample of a ceramic susceptor according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As a result of investigating the degree of planarization in thewafer-carrying face of ceramic susceptors for semiconductormanufacturing equipment, the present inventors discovered that withconventional ceramic susceptors, the wafer-carrying face in general atordinary temperature is in a warped state in which it trends convex(which hereinafter will also be termed the “plus direction”), whereinwhen the temperature rises by electricity being passed into theresistive heating element, lowering the Young's modulus, theplus-direction warpage becomes greater.

To address this, in the present invention, by modulating the warpedstate of the ceramic susceptor at ordinary temperature so that thewafer-carrying face trends concave (which hereinafter will also betermed the “minus direction”), heightening the degree of planarizationof the wafer-carrying face in its high-temperature region overconventional levels when in practice a wafer is being treated waspossible. In particular, with a ceramic susceptor of the presentinvention, the wafer-carrying face in arched contour when not heating(when at ordinary temperatures) is rendered a concavity of 0.001 to 0.7mm per 300 mm length along the wafer-carrying face.

By rendering this sort of arched contour in the ceramic susceptor atordinary temperature, during actual processing of a wafer the susceptorin the high-temperature region flexes in the plus direction, whichtherefore enhances the degree of planarization of the wafer-carryingface and practically eliminates gaps between it and the wafer. As aresult, bringing wafer-surface isothermal ratings to within ±5% withceramic susceptors whose thermal conductivity is 100 W/mK or more, andto within ±1.0% with ceramic susceptors of 10 to 100 W/mK, is possiblein the present invention.

Next, a specific structure for a ceramic susceptor that is given by thepresent invention will be explained according to FIGS. 1 and 2. Theceramic susceptor 1 depicted in FIG. 1 is provided on one surface of itsceramic substrate 2 a with a resistive heating element 3 of apredetermined circuit pattern, and a separate ceramic substrate 2 b isjoined onto that surface by means of a bonding layer 4 made out of glassor ceramic. Here, the circuit pattern for the resistive heating element3 is formed so that for example the linewidth and line spacing will be 5mm or less, more preferably 1 mm or less.

Likewise, a ceramic susceptor 11 depicted in FIG. 2 is in the interiorthereof furnished with a resistive heating element 13 and meanwhile witha plasma electrode 15. In particular, similarly to the ceramic susceptor1 of FIG. 1, a ceramic substrate 12 a that on one surface has theresistive heating element 13 is joined to a ceramic substrate 12 b witha bonding layer 4, but meanwhile a separate ceramic substrate 12 c onwhich the plasma electrode 15 is provided is joined to the other surfaceof the ceramic substrate 12 a by means of a bonding layer 14 b made outof glass or ceramic.

It should be understood that in manufacturing the ceramic susceptorsrepresented in FIGS. 1 and 2, apart from the method of joining therespective ceramic substrates, green sheets of approximately 0.5 mmthickness may be prepared, and after utilizing an electricallyconductive paste to print-coat onto each green sheet circuit patternsfor the resistive heating element and/or the plasma electrode, thesegreen sheets, as well as ordinary green sheets as needed, may belaminated to produce the required thickness and made unitary bysintering them simultaneously.

EMBODIMENTS Embodiment 1

A sintering additive and a binder were added to, and, using a ball mill,dispersed into and mixed with, aluminum nitride (AlN) powder. Afterdrying it with a spray dryer, the powder blend was press-molded intodiscoid plates of 380 mm diameter and 1 mm thickness. Sintered AlNcompacts were produced by degreasing, within a non-oxidizing atmosphereat a temperature of 800° C., the obtained molded objects and thensintering them 4 hours at a temperature of 1900° C. The thermalconductivity of the AlN sinters was 170 W/mK. The circumferentialsurface of the sintered AlN compacts was polished to bring their outerdiameter down to 300 mm, whereby disk pairs of AlN substrates forceramic susceptors were prepared.

A paste, being tungsten powder and a sintering additive knead-mixed intoa binder, was print-coated to form a predetermined heating-elementcircuit pattern onto a face of first disks from the AlN substrate pairs.Resistive heating elements of tungsten were formed by degreasing theseAlN substrates within a non-oxidizing atmosphere at a temperature of800° C., and then baking them at a temperature of 1700° C.

A paste in which a Y₂O₃ adhesive agent and a binder were knead-mixed wasprint-coated onto a face of the remaining, second disks from the AlNsubstrate pairs, which were then degreased at a temperature of 500° C.This adhesive-agent layer on the AlN second substrate disks was overlaidonto the side of the first AlN substrate disks where the resistiveheating element was formed, and the first/second disk pairs were bondedtogether by heating them at a temperature of 800° C., whereby ceramicsusceptors made of AlN were produced.

In addition, pipe-shaped support members made out of sintered AlNmaterial were produced by compacting the foregoing spray-dried aluminumnitride powder in a cold isostatic press (CIP) at 1 ton/cm² so as tomold compacts whose post-sintering dimensions would be 100 mm outsidediameter, 90 mm inside diameter, and 200 mm length, and degreasing thecompacts within a non-oxidizing atmosphere at 800° C. and baking them 4hours at 1900° C.

One end face of the AlN pipe-shaped support members was set in place inthe center of the AlN ceramic susceptors and hot-press joined to them byheating 2 hours at a temperature of 800° C. In doing so, by modulatingwarpage in the sample holder when the hot-press joint formed, theinitial warpage in the ceramic susceptors following joint formation wasvaried sample by sample to be the values set forth in Table I below.

To evaluate the ceramic susceptors thus produced having the FIG. 1structure, the susceptor temperature was elevated to 500° C. by passingan electric current into the resistive heating element at a voltage of200 V, through twin electrodes formed on the surface of the susceptor onthe side opposite its wafer-carrying face, wherein warpage at 500° C. inthe wafer-carrying face of the ceramic susceptors was measured.

In addition, a silicon wafer of 0.8 mm thickness and 300 mm diameter wasset atop the wafer-carrying face of the ceramic susceptors, and theisothermal rating of the wafer surface was found by measuring the wafersurface-temperature distribution during the time the susceptor washeated to 500° C. as just noted. The results obtained are shown in TableI below for each of the samples. It should be understood that in thewarpage columns in Table I, “+” indicates that the flexing direction isthe plus direction (convexity), and “−,” that the fixing direction isthe minus direction (concavity). (The same is true for each of tables inthe following.) TABLE I Initial warpage 500° C. warpage Wafer-surfaceisothermal Sample (mm/300 mm) (mm/300 mm) rating at 500° C. (%) 1* ±0.03+0.6 ±0.9 2* ±0.0 +0.51 ±0.7 3  −0.001 +0.45 ±0.5 4  −0.1 +0.4 ±0.45 5 −0.5 +0.03 ±0.4 6  −0.7 −0.2 ±0.5 7* −0.8 −0.5 ±0.62 8* −1.0 −0.7 ±0.85Note:Samples marked with an asterisk (*) in the table are comparativeexamples.

As indicated in the above Table I, in order to obtain sought-afterwafer-surface isothermal ratings (within ±0.5%) in ceramic susceptorsmade of AlN, the susceptor wafer-carrying face in an initial archedcontour must be rendered a concavity of within a range of 0.001 to 0.7mm/300 mm.

Embodiment 2

A sintering additive and a binder were added to, and, using a ball mill,dispersed into and mixed with, silicon nitride (Si₃N₄) powder. Afterdrying it with a spray dryer, the powder blend was press-molded intodiscoid plates of 380 mm diameter and 1 mm thickness. Sintered Si₃N₄compacts were produced by degreasing, within a non-oxidizing atmosphereat a temperature of 800° C., the molded objects and then sintering them4 hours at a temperature of 1550° C. The thermal conductivity of thesintered Si₃N₄ compacts was 20 W/mK. The circumferential surface of thesintered Si₃N₄ compacts was polished to bring their outer diameter downto 300 mm, whereby disk pairs of Si₃N₄ substrates for ceramic susceptorswere prepared.

Resistive heating elements of tungsten were formed onto a face of firstdisks from the Si₃N₄ substrate pairs by the same method as inEmbodiment 1. An SiO₂ adhesive-agent layer was formed superficially ontothe remaining, second disks from the Si₃N₄ substrate pairs, which wereoverlaid onto the side of the first Si₃N₄ substrate disks where theresistive heating element was formed, and the first/second disk pairswere bonded together by heating them at a temperature of 800° C.,whereby ceramic susceptors made of Si₃N₄ were produced.

In addition, pipe-shaped support members made out of sintered Si₃N₄material were produced by compacting the foregoing spray-dried siliconnitride powder in a CIP at 1 ton/cm² so as to mold compacts whosepost-sintering dimensions would be 100 mm outside diameter, 90 mm insidediameter, and 200 mm length, and degreasing the compacts within anon-oxidizing atmosphere at a temperature of 800° C. and baking them 4hours at 1900° C.

One end face of the Si₃N₄ pipe-shaped support members was set in placein the center of the Si₃N₄ ceramic susceptors and joined to them byheating 2 hours at a temperature of 800° C. In doing so, by modulatingwarpage in the sample holder when the hot-press joint formed, theinitial warpage in the ceramic susceptors following joint formation wasvaried sample by sample to be the values set forth in Table II below.

To evaluate the ceramic susceptors thus produced having the FIG. 1structure, the susceptor temperature was elevated to 500° C. by passingan electric current into the resistive heating element at a voltage of200 V, through twin electrodes formed on the surface of the susceptor onthe side opposite its wafer-carrying face, wherein warpage in thewafer-carrying face at 500° C. was measured. In addition, the isothermalrating of a silicon wafer of 0.8 mm thickness and 300 mm diameter setatop the wafer-carrying face of the ceramic susceptors was found bymeasuring the wafer surface-temperature distribution. The resultsobtained are shown in Table II below for each of the samples. TABLE IIInitial warpage 500° C. warpage Wafer-surface isothermal Sample (mm/300mm) (mm/300 mm) rating at 500° C. (%)  9* ±0.0 +0.54 ±1.21 10 −0.003+0.46 ±0.98 11 −0.12 +0.4 ±0.90 12 −0.5 +0.03 ±0.76 13 −0.65 −0.2 ±0.98 14* −0.8 −0.55 ±1.19Note:Samples marked with an asterisk (*) in the table are comparativeexamples.

As indicated in the above Table II, also with silicon-nitride ceramicsusceptors whose thermal conductivity is 20 W/mK, by rendering thesusceptor wafer-carrying face in an initial arched contour to be aconcavity of within a range of 0.001 to 0.7 mm/300 mm in the minusdirection, sought-after wafer-surface isothermal ratings (within +1.0%)could be procured.

Embodiment 3

A sintering additive and a binder were added to, and, using a ball mill,dispersed into and mixed with, aluminum oxynitride (AlON) powder. Afterdrying it with a spray dryer, the powder blend was press-molded intodiscoid plates of 380 mm diameter and 1 mm thickness. Sintered AlONcompacts were produced by degreasing, within a non-oxidizing atmosphereat a temperature of 800° C., the molded objects and then sintering them4 hours at a temperature of 1770° C. The thermal conductivity of thesintered AlON compacts was 20 W/mK. The circumferential surface of theobtained sintered AlON compacts was polished to bring their outerdiameter down to 300 mm, whereby disk pairs of AlON substrates forceramic susceptors were prepared.

Resistive heating elements of tungsten were formed onto a face of firstdisks from the AlON substrate pairs by the same method as inEmbodiment 1. An SiO₂ adhesive-agent layer was formed superficially ontothe remaining, second disks from the AlON substrate pairs, which wereoverlaid onto the side of the first AlON substrate disks where theresistive heating element was formed, and the first/second disk pairswere bonded together by heating them at a temperature of 800° C.,whereby ceramic susceptors made of AlON were produced.

In addition, pipe-shaped support members made out of sintered AlONmaterial were produced by compacting the foregoing spray-dried aluminumoxynitride powder in a CIP at 1 ton/cm² so as to mold compacts whosepost-sintering dimensions would be 100 mm outside diameter, 90 mm insidediameter, and 200 mm length, and degreasing the compacts within anon-oxidizing atmosphere at 800° C. and baking them 4 hours at 1900° C.

One end face of the AlON pipe-shaped support members was set in place inthe center of the AlON ceramic susceptors and joined to them by heating2 hours at a temperature of 800° C. In doing so, by modulating warpagein the sample holder when the hot-press joint formed, the initialwarpage in the ceramic susceptors following joint formation was variedsample by sample to be the values set forth in Table III below.

To evaluate the ceramic susceptors thus produced having the FIG. 1structure, the susceptor temperature was elevated to 500° C. by passingan electric current into the resistive heating element at a voltage of200 V, through twin electrodes formed on the surface of the susceptor onthe side opposite its wafer-carrying face, wherein warpage in thewafer-carrying face at 500° C. was measured. In addition, the isothermalrating of a silicon wafer of 0.8 mm thickness and 300 mm diameter setatop the wafer-carrying face of the ceramic susceptors was found bymeasuring the wafer surface-temperature distribution. The resultsobtained are shown in Table III below for each of the samples. TABLE IIIInitial warpage 500° C. warpage Wafer-surface isothermal Sample (mm/300mm) (mm/300 mm) rating at 500° C. (%)  15* ±0.0 +0.55 ±1.18 16 −0.001+0.45 ±1.00 17 −0.09 +0.4 ±0.86 18 −0.45 +0.03 ±0.80 19 −0.7 −0.2 ±1.00 20* −0.8 −0.5 ±1.20Note:Samples marked with an asterisk (*) in the table are comparativeexamples.

As indicated in the above Table III, also with aluminum oxynitrideceramic susceptors whose thermal conductivity is 20 W/mK, by renderingthe susceptor wafer-carrying face in an initial arched contour to be aconcavity of within a range of 0.001 to 0.7 mm/300 mm in the minusdirection, sought-after wafer-surface isothermal ratings (within ±1.0%)could be procured.

Embodiment 4

Disk pairs of ceramic-susceptor AlN substrates 300 mm in diameter, madeout of sintered aluminum nitride material, as well as pipe-shapedsupport members made of AlN, were manufactured by the same method as inEmbodiment 1.

Next, in utilizing the AlN substrate pairs to fabricate ceramicsusceptors, the material for the resistive heating element provided onthe one face of the first disks from the AlN substrate pairs wasswitched to Mo, to Pt, to Ag—Pd, and to Ni—Cr, respective pastes ofwhich were printed-coated, and fired within a non-oxidizing atmosphere,onto respective first-disk faces.

After that the remaining, second disks from the AlN substrate pairs werecoated with an SiO₂ bonding agent and overlaid onto the side of thefirst AlN substrate disks where the resistive heating element wasformed, wherein AlN ceramic susceptors were produced in the same manneras in Embodiment 1, apart from the SiO₂ bonding agent also being appliedto where the joint with the pipe-shaped support member made of AlN was,and the susceptors being degreased at 800° C. in a non-oxidizingatmosphere to bond the joints at 800° C. In doing so, by modulatingwarpage in the sample holder when the joint formed, the initial warpagein the ceramic susceptors following joint formation was varied sample bysample to be the values set forth in Table IV below.

To evaluate the ceramic susceptors thus produced differing inresistive-heating-element substance, the susceptor temperature waselevated to 500° C. by passing an electric current into the resistiveheating element at a voltage of 200 V, through twin electrodes formed onthe surface of the susceptor on the side opposite its wafer-carryingface, wherein warpage in the wafer-carrying face at 500° C. wasmeasured. In addition, the isothermal rating of a silicon wafer of 0.8mm thickness and 300 mm diameter set atop the wafer-carrying face of theceramic susceptors was found by measuring the wafer surface-temperaturedistribution. The results obtained are shown in Table IV below for eachof the samples. TABLE IV Resistive heating Initial warpage Wafer-surfaceisothermal Sample element (mm/300 mm) rating (%) at 500° C.  21* Mo ±0.0±0.64 22 Mo −0.002 ±0.45 23 Mo −0.11 ±0.43 24 Mo −0.55 ±0.43 25 Mo −0.69±0.5  26* Mo −0.8 ±0.54  27* Pt ±0.0 ±0.62 28 Pt −0.001 ±0.5 29 Pt −0.09±0.43 30 Pt −0.45 ±0.4 31 Pt −0.7 ±0.5  32* Pt −0.8 ±0.63  33* Ag—Pd±0.0 ±0.67 34 Ag—Pd −0.003 ±0.5 35 Ag—Pd −0.12 ±0.45 36 Ag—Pd −0.5 ±0.437 Ag—Pd −0.68 ±0.5  38* Ag—Pd −0.8 ±0.56  39* Ni—Cr ±0.0 ±0.61 40 Ni—Cr−0.001 ±0.46 41 Ni—Cr −0.09 ±0.43 42 Ni—Cr −0.45 ±0.4 43 Ni—Cr −0.7 ±0.5 44* Ni—Cr −0.8 ±0.61Note:Samples marked with an asterisk (*) in the table are comparativeexamples.

As indicated in Table IV above, with cases where the resistive heatingelement was Mo, Pt, Ag—Pd and Ni—Cr, by rendering the susceptorwafer-carrying face in an initial arched contour to be a concavity ofwithin a range of 0.001 to 0.7 mm/300 mm in the minus direction,favorable results similar to those in Embodiment 1 in terms ofwafer-surface isothermal ratings during the heating operation could beprocured.

Embodiment 5

Utilizing a paste in which a sintering additive, a binder, a dispersingagent and alcohol were added and knead-mixed into aluminum nitridepowder, green sheets approximately 0.5 mm in thickness were produced bymolding using a doctor-blading technique.

Next, after drying the green sheets 5 hours at 80° C. aresistive-heating-element layer in a given circuit pattern was formed byprint-coating a paste, in which tungsten powder and a sintering additivewere knead-mixed with a binder, onto a face of single plies of the greensheets. In addition, a plasma electrode layer was formed byprint-coating the tungsten paste just described onto a face of separatesingle plies of the green sheets that had been likewise dried. The 2plies of the green sheets having electrically conductive layers werelaminated in 50 plies total with green sheets on which no conductivelayer had been printed, and the laminates were united by heating them ata temperature of 140° C. while subjecting them to a pressure of 70kg/cm².

After being degreased 5 hours within a non-oxidizing atmosphere at 600°C., the obtained laminates were hot-pressed at 100 to 150 kg/cm²pressure and 1800° C. temperature to produce aluminum nitride platematerial of 3 mm thickness. This was cut out into discoid plates of 380mm diameter, the periphery of which was polished down until the plateswere 300 mm in diameter, whereby AlN ceramic susceptors of the FIG. 2structure, internally having a resistive heating element and plasmaelectrodes were produced.

An end face of AlN pipe-shaped support members fashioned by the samemethod as in Embodiment 1 was set in place in the center of theabove-described ceramic susceptors and joined to them by heating 2 hoursat a temperature of 800° C. Here, by modulating warpage in the sampleholder when the joint formed, the initial warpage in the ceramicsusceptors following joint formation was varied sample by sample to bethe values set forth in Table V below.

To evaluate the ceramic susceptors produced in this way, the susceptortemperature was elevated to 500° C. by passing an electric current intothe resistive heating element at a voltage of 200 V, through twinelectrodes formed on the surface of the susceptor on the side oppositeits wafer-carrying face, wherein warpage in the wafer-carrying face at500° C. was measured. In addition, the isothermal rating of a siliconwafer of 0.8 mm thickness and 300 mm diameter set atop thewafer-carrying face of the ceramic susceptors was found by measuring thewafer surface-temperature distribution. The results obtained are shownin Table V below for each of the samples. TABLE V Initial warpage 500°C. warpage Wafer-surface isothermal Sample (mm/300 mm) (mm/300 mm)rating at 500° C. (%)  45* ±0.0 +0.57 ±0.61 46 −0.001 +0.46 ±0.48 47−0.09 +0.4 ±0.43 48 −0.53 +0.03 ±0.38 49 −0.67 −0.2 ±0.49  50* −0.80−0.55 ±0.61Note:Samples marked with an asterisk (*) in the table are comparativeexamples.

As indicated in the above Table V, also with ceramic susceptors having aresistive heating element and plasma electrodes, by rendering thesusceptor wafer-carrying face in an initial arched contour to be aconcavity of within a range of 0.001 to 0.7 mm/300 mm in the minusdirection, favorable results with regard to wafer-surface isothermalratings during the heating operation could be procured.

INDUSTRIAL APPLICABILITY

In accordance with the present invention, heightening the degree ofplanarization of the wafer-carrying face of ceramic susceptors in thehigh-temperature region thereof where wafers are processed in the courseof manufacturing semiconductors affords susceptors for semiconductormanufacturing equipment in which wafer-surface isothermal quality duringheating operations is heightened.

1. For semiconductor manufacturing equipment, a ceramic susceptorcomprising: a ceramic substrate; a resistive heating element formedeither superficially or interiorly in said ceramic substrate; and aconcavity molded in a wafer-carrying face defined on a surface of saidceramic substrate through which said resistive heating element issuesheat when the susceptor performs a heating operation, said concavitybeing 0.001 to 0.7 mm/300 mm in negative arched contour when thesusceptor is not heating.
 2. A ceramic susceptor as set forth in claim1, wherein the ceramic substrate is made of at least one ceramicselected from aluminum nitride, silicon nitride, aluminum oxynitride,and silicon carbide.
 3. A ceramic susceptor as set forth in claim 1,wherein the resistive heating element is made from at least one metalselected from tungsten, molybdenum, platinum, palladium, silver, nickel,and chrome.
 4. A ceramic susceptor as set forth in claim 1, furthercomprising a plasma electrode disposed either in the surface or in theinterior of said ceramic substrate.
 5. A ceramic susceptor as set forthin claim 2, wherein the resistive heating element is made from at leastone metal selected from tungsten, molybdenum, platinum, palladium,silver, nickel, and chrome.
 6. A ceramic susceptor as set forth in claim2, further comprising a plasma electrode disposed either in the surfaceor in the interior of said ceramic substrate.
 7. A ceramic susceptor asset forth in claim 3, further comprising a plasma electrode disposedeither in the surface or in the interior of said ceramic substrate.
 8. Aceramic susceptor as set forth in claim 5, further comprising a plasmaelectrode disposed either in the surface or in the interior of saidceramic substrate.